Samir Hussein/WireImage(LONDON) -- There’s still great excitement in Great Britain over Monday’s birth of a baby boy to Kate Middleton, Duchess of Cambridge, and Prince William at St. Mary's Hospital in London.

The couple’s first child, who is third in line to the British throne after his father and his grandfather, Prince Charles, weighed in at 8 lbs 6 oz. Both mother and child are doing well and remained in the hospital overnight.

In a short statement, William, who was present for the birth, said, “We could not be happier.” He spent the night in the hospital with his wife and new son.

The baby's name is expected to be revealed soon. When that happens, he'll be referred to as "His Royal Highness Prince [Name] of Cambridge."

Queen Elizabeth II, the baby’s great-grandmother, has been on the throne for 61 years. The newly-born prince is her third great-grandchild.

The announcement of the baby’s birth came after Middleton had been in the hospital for more than 14 hours, although the baby was born several hours before the birth was made public to Londoners and the rest of the world.

Cheers erupted at St. Mary's Hospital and Buckingham Palace when the news was released.

Throngs of people gathered outside of the palace to wait for the formal, signed birth announcement that was driven from the hospital to the palace. Following tradition, the document was taken into the palace to be shown to the queen before it was placed on an easel in the palace court.

"The Queen and Prince Philip are delighted at the news of the birth of The Duke and Duchess of Cambridge's baby," the British monarchy's official Twitter account posted.

Charles also expressed his joy about being a first-time grandfather. In a statement, he said, "Both my wife and I are overjoyed at the arrival of my first grandchild. It is an incredibly special moment for William and Catherine and we are so thrilled for them on the birth of their baby boy."

"Grandparenthood is a unique moment in anyone's life, as countless kind people have told me in recent months, so I am enormously proud and happy to be a grandfather for the first time and we are eagerly looking forward to seeing the baby in the near future," he added.